This application solves the problem of calculating the pricing for ski lift passes. There's some intricate logic linked to what kind of lift pass you want, your age and the specific date at which you'd like to ski. There's a new feature request, be able to get the price for several lift passes, not just one. Currently the pricing for a single lift pass is implemented, unfortunately the code as it is designed is not reusable. You could put some high level tests in place in order to do preparatory refactoring so that the new feature requires minimum effort to implement.
This kata models a common problem - code that makes no sense to unit test due to bad design.
You can find a video pitch here
There are a few steps, you could do any of them.
- Cover with high level tests.
- Refactor the code to maximize unit testability and reuse for the new feature
- Pull down most of the high level tests
- Implement the new feature using unit tests and 1 or 2 high level tests.
Set up a MySQL database on localhost 3306 with user root and password mysql.
If you have Docker installed the easiest thing is to use this script, that will initialize a MariaDB.
./runLocalDatabase.sh
Inject the data with
mysql -u root -p mysql < ./database/initDatabase.sql
Then head on to the language of your choice and follow the Readme in there.
There's a good chance you could find a design that is both easier to test, faster to work with and that solves the problem with minimum amount of code. One such design would be to rid the bulk of the logic from it's adherence to the http/rest framework and from the sql specificities. This is sometimes called hexagonal architecture and it facilitates respecting the Testing Pyramid which is not currently possible - there can be only top-level tests
The typical workflow would be
- Cover everything from the http layer, use a real DB
- Separate request data extraction and sending the response from the logic
- Extract a method with the pure logic, move that method to an object (ex PricingLogic)
- Now extract the sql stuff from PricingLogic, first to some method with a signature that has nothing to do with sql, then move these methods to a new class (ex PricingDao)
- There should be ~3/4 elements, the http layer should have the PricingLogic as an injected dependency and the PricingLogic should have the PricingDao as an injected dependency.
- Move the bulk of the high level tests down onto PricingLogic using a fake dao, write some focused integration tests for the PricingDao using a real DB, there should be only a handful.
Now the HTTP layer and the integration of the parts can be tested with very few (one or two) high-level tests.
Try it first ;)